1. Field of the Invention
This invention relates to a parallax image input apparatus. This invention particularly relates to a novel apparatus for acquiring a plurality of images having parallax.
2. Description of the Prior Art
Techniques for detecting the information concerning the depth direction of an object by utilization of parallax images and restoring the information belong to the field of "computer vision" or "image understanding" in research of image processing. The techniques are considered as being important for realization of artificial visual functions.
As techniques for inputting parallax images, various techniques utilizing two cameras, which are located so as to simulate the binocular vision of the human, have heretofore been proposed. Such techniques are described in, for example, "Computer Vision" by Koichiro Deguchi, Maruzen, pp. 83-88, and "Image Processing Handbook" by Morio Ogami, Shokodo, pp. 395-397. Techniques utilizing three or more cameras have also been proposed. The techniques utilizing three or more cameras are described in, for example, "Object Detection Using Multiview Stereo Images" by Omori and Morishita, SICE collected papers, Vol. 18, 7, pp. 716-722, July 1982; "Recognition of Three-Dimensional Object Using Multiple Images" by Masahiko Taniuchida, Nikkei Mechanical, Vol.157, pp.82-91, January 1984; "Stereo Vision Corresponding Points Processing with Trinocular Images" by Itoh and Ishii, 29'th national meeting of Information Processing Society of Japan, 2M-3, September 1984; and "Trinocular Vision Stereo" by Ota and Ikeda, ibid., 2M-4. These techniques are referred to as the compound eye stereoscopic techniques.
However, the aforesaid proposed techniques have the practical drawbacks in that the apparatuses cannot be kept small in size and cheap in cost, and in that complicated adjustments are required with regard to the direction of each camera, the focusing point of each camera, and other factors.
Further, as different techniques for inputting parallax images, techniques for successively moving a single camera and thereby acquiring parallax images have been proposed. Such techniques are described in, for example, "Determining Three-Dimensional Structure From Image Sequences given by Horizontal and Vertical Moving Camera" by Yamamoto, collected papers of The Institute of Electronics and Communication Engineers of Japan, Vol. J69-D, No. 11, 1631; "Depth measurement by motion stereo" by R. Nevatia, Comput. Graphics Image Process., Vol. 9, pp. 23-214, 1976; "Depth from camera motion in a real world scene" by T. D. Williams, IEEE Trans. Pattern Anal. Mach. Intell., PAMI-2, pp. 511-516, 1980. With the proposed techniques, parallax images are obtained as time series continuous images. The proposed techniques are referred to as the motion stereoscopic techniques. With the motion stereoscopic techniques, parallax images seen from a markedly larger number of viewpoints than in the aforesaid compound eye stereoscopic techniques can be obtained. A plurality of parallax images, which have been sampled at a high density such that they may have only a slight parallax, are referred to as the continuous parallax images. With the motion stereoscopic techniques, since it is sufficient for only a single camera to be used, the problems with regard to the adjustments of the cameras with respect to one another, the matching of the camera positions, and the like, as in the aforesaid compound eye stereoscopic techniques can be avoided.
However, with the motion stereoscopic techniques, since the camera must be successively translated to positions having been set previously, it is necessary for a large-scale translation mechanism to be used. In general, a track, such as a rail, is constructed, or an accurate moving stage is located. Also, a drive device for translating the camera is used. Thus the motion stereoscopic techniques require complicated mechanisms, and therefore cannot be practical.